A holistic framework for the optimal design and operation of electricity, heating, cooling and hydrogen technologies in buildings

In this work, the Design and Operation of Integrated Technologies (DO-IT) framework is developed, a comprehensive tool to support short- and long-term technology investment and operation decisions for integrated energy generation, conversion and storage technologies in buildings. The novelty of this framework lies in two key aspects: firstly, it integrates essential open-source modelling tools covering energy end uses in buildings, technology performance and cost, and energy system design optimisation into a unified and easily-reproducible framework. Secondly, it introduces a novel optimisation tool with a concise and generic mathematical formulation capable of modelling multi-energy vector systems, capturing interdependencies between different energy vectors and technologies. The model formulation, which captures both short- and long-term energy storage, facilitates the identification of smart design and operation strategies with low computational cost. Different building energy demand and price scenarios are investigated and the economic and energy benefits of using a holistic multi-energy-vector approach are quantified. Technology combinations under consideration include: (i) a photovoltaic-electric heat pump-battery system, (ii) a photovoltaic-electric heat pump-battery-hot water cylinder system, (iii) a photovoltaic-electrolyser‑hydrogen storage-fuel cell system, and (iv) a system with all above technology options. Using a university building as a case study, it is shown that the smart integration of electricity, heating, cooling and hydrogen generation and storage technologies results in a total system cost which is >25% lower than the scenario of only importing grid electricity and using a fuel oil boiler. The battery mitigates intra-day fluctuations in electricity demand, and the hot-water cylinder allows for efficiently managing heat demand with a small heat pump. In order to avoid PV curtailment, excess PV-generated electricity can also be stored in the form of green hydrogen, providing a long-term energy storage solution spanning days, weeks, or even seasons. Results are useful for end-users, investment decision makers and energy policy makers when selecting building-integrated low-carbon technologies and relevant policies.